Extra Field Research Articles

Asymmetric conductivity of the Kondo effect in cold atomic systems

Motivated by recent theoretical and experimental advances in quantum simulations using alkaline earth (AE) atoms, we put forward a proposal to detect the Kondo physics in a cold atomic system. It has been demonstrated that the intrinsic spin-exchange interaction in AE atoms can be significantly enhanced near a confinement-induced resonance (CIR), which facilitates the simulation of Kondo physics. Since the Kondo effect appears only for antiferromagnetic coupling, we find that the conductivity of such system exhibits an asymmetry across a resonance of spin-exchange interaction. The asymmetric conductivity can serve as the smoking gun evidence for Kondo physics in the cold atom context. When an extra magnetic field ramps up, the spin-exchange process near Fermi surface is suppressed by Zee-man energy and the conductivity becomes more and more symmetric. Our results can be verified in the current experimental setup.

Aspects of two-dimensional dilaton gravity, dimensional reduction, and holography

We discuss aspects of generic 2-dimensional dilaton gravity theories. The 2-dim geometry is in general conformal to $AdS_2$ and has IR curvature singularities at zero temperature: this can be regulated by a black hole. The on-shell action is divergent: we discuss the holographic energy-momentum tensor by adding appropriate counterterms. For theories obtained by dimensional reduction of the gravitational sector of higher dimensional theories, for instance higher dimensional $AdS$ gravity as a concrete example, the 2-dimensional description dovetails with the higher dimensional one. We also discuss more general theories containing an extra scalar field which now drives nontrivial dynamics. Finally we discuss aspects of the 2-dimensional cosmological singularities discussed in earlier work. These studies suggest that generic 2-dim dilaton gravity theories are somewhat distinct from JT gravity and theories "near JT".

Minimal twist for the Standard Model in noncommutative geometry: The field content

Noncommutative geometry provides both a unified description of the Standard Model of particle physics together with Einstein-Hilbert action (in euclidean signature) and some tools to go beyond the Standard Model. In this paper, we extend to the full noncommutative geometry of the Standard Model the twist (in the sense of Connes-Moscovici) initially worked out for the electroweak sector and the free Dirac operator only. Namely, we apply the twist also to the strong interaction sector and the finite part of the Dirac operator. To do so, we are forced to take into account a violation of the twisted first-order condition. As a result, we still obtain the extra scalar field required to stabilise the electroweak vacuum and fit the Higgs mass, but it now has two chiral components. We also get the additive field of 1-forms already pointed out in the electroweak model, but with a richer structure. Finally, we obtain a pair of Higgs doublets, which are expected to combine into a single Higgs doublet in the action formula, as will be investigated in the second part of this work.

Alloyed AuPt nanoframes loaded on h-BN nanosheets as an ingenious ultrasensitive near-infrared photoelectrochemical biosensor for accurate monitoring glucose in human tears

Photo-electro-chemical (PEC) glucose biosensor has recently attracted extensive attention due to the double advantages of both photocatalysis via photon energy utilization and electrocatalytic oxidation through extra electric field. Compared with previous shorter wavelength (violet-visible) light-induced PEC reaction, the anticipated near infrared (NIR, >~700 nm) excited PEC biosensor with multiple fascinating features should be more suitable for clinical diagnostic biology. Herein, we report an ingenious NIR-PEC biosensor by loading alloyed Au5Pt9 nanoframes on two dimensional (2D) hexagonal boron nitride (h-BN) nanosheets. The obtained h-BN/Au5Pt9 nanoframes exhibit a remarkable higher NIR-PEC activity in comparison with other as-prepared h-BN/AuPt references. The improved PEC performance is attributed to the enhanced synergetic coupling effect between Au5Pt9 nanoalloys and constitutionally stable h-BN that gives rise to a stronger absorbance capacity and pronounced localized surface plasmon resonance (LSPR) in visible-NIR region as well as high free-electron mobility of framework-like Au/Pt. Interestingly, the obtained h-BN/Au5Pt9 nanoframes excited by 808 nm NIR light provide superior PEC accuracy and sensitivity as compared to visible or other NIR light irradiation. Then, the novel 808 nm NIR-PEC biosensor was used for precise glucose monitoring in human tears with a detectable concentration of 0.03~100 μM and a low detection limit of 0.406 nM. Undoubtedly, the proposed h-BN/Au5Pt9 nanoframes as an appealing NIR-PEC glucose biosensor can possess greater potential values for practical glucose monitoring in biomedicine.

Binary black hole system at equilibrium

An exact and analytical solution of four dimensional vacuum General Relativity representing a system of two static black holes at equilibrium is presented. The metric is completely regular outside the event horizons, both from curvature and conical singularities. The balance between the two Schwarzschild sources is granted by an external gravitational field, without the need of extra matter fields besides gravity, nor strings or struts. The geometry of the solution is analysed. The Smarr law, the first and the second law of black hole thermodynamics are discussed.

Dark matter from a dark connection

In the first part of this note, we observe that a non-Riemannian piece in the affine connection (a “dark connection”) leads to an algebraically determined, conserved, symmetric 2-tensor in the Einstein field equations that is a natural dark matter candidate. The only other effect it has, is through its coupling to standard model fermions via covariant derivatives. If the local dark matter density is the result of a background classical dark connection, these Yukawa-like mass corrections are minuscule ([Formula: see text] for terrestrial fermions) and none of the tests of general relativity or the equivalence principle are affected. In the second part of the note, we give dynamics to the dark connection and show how it can be re-interpreted in terms of conventional dark matter particles. The simplest way to do this is to treat it as a composite field involving scalars or vectors. The (pseudo-)scalar model naturally has a perturbative shift-symmetry and leads to versions of the Fuzzy Dark Matter (FDM) scenario that has recently become popular (e.g. arXiv:1610.08297) as an alternative to WIMPs. A vector model with a [Formula: see text]-parity falls into the Planckian Interacting Dark Matter (PIDM) paradigm, introduced in arXiv:1511.03278. It is possible to construct versions of these theories that yield the correct relic density, fit with inflation and are falsifiable in the next round of CMB experiments. Our work is an explicit demonstration that the meaningful distinction is not between gravity modification and dark matter, but between theories with extra fields and those without.

Traversable wormholes in the galactic halo with MOND and non-linear equation of state

The existence of traversable wormhole (TW) in the Einstein’s general theory of relativity is explored with density profile obtained from modified Newtonian dynamics (MOND) with or without a scalar field. The shape functions for wormholes and the null energy conditions (NEC) of matter in the wormhole are determined with a constant redshift function. Wormholes are found to exist with MOND density profile in the presence of exotic matter and determine the mass of a asymptotic flat wormhole geometry. The addition of an extra massless scalar field with MOND density profile permits wormholes even when NEC is obeyed at the throat depending on the initial value of the scalar field. Considering a non-linear equation of state (EoS) , (where A, B and ρ c are constants) in Einstein gravity we obtain TW. In this case new classes of TW solutions are determined which depends on the EoS parameters A and B. TW exists with normal matter when ρ(r 0) ⩾ ρ c and with exotic matter when ρ(r 0) < ρ c at the throat where .

Novel in-situ electroflotation driven by hydrogen evolution reaction (HER) with polypyrrole (PPy)-Ni-modified fabric membrane for efficient oil/water separation

Efficient separation of oil/water emulsion is still a worldwide challenge. Herein, a new conception/strategy of in-situ electroflotation driven by hydrogen evolution reaction (HER) combining with a polypyrrole (PPy)-Ni-modified fabric membrane was proposed for efficient oil/water separation. To realize this new conception, nickel-decorated polyester fabric membrane was successfully fabricated via facile electroless Ni plating process on the polypyrrole (PPy)-modified surface. The Ni-decorated fabric membrane processed superhydrophilicity, underwater superoleophobicity and excellent electrical conductivity (electrical resistance of ~14.1 Ω), which could serve as cathode for HER. The fabric membrane itself couldn't separate oil/water emulsion, but achieved extremely high permeation (above 12526.5 L m−2 h−1) and oil rejection (above 98.6%) for separating stratified oil/water mixtures under gravity force. By applying an extra electric field on the conductive fabric membrane, an in-situ electroflotation process driven by HER can be produced. Under the optimized electroflotation conditions (20.0 V cm−1 electric field intensity, 20 g L−1 electrolyte concentration and 30 min electroflotation time) in this study, this new process could efficiently separate oil/water emulsion with high permeation flux (840.6 L m−2 h−1) and oil rejection (98.5%). The present work provided a new conception of in-situ electroflotation-membrane separation process for treatment of oily wastewater, showing strong application significance.

Extended Chern–Simons Model for a Vector Multiplet

We consider a gauge theory of vector fields in 3D Minkowski space. At the free level, the dynamical variables are subjected to the extended Chern–Simons (ECS) equations with higher derivatives. If the color index takes n values, the third-order model admits a 2n-parameter series of second-rank conserved tensors, which includes the canonical energy–momentum. Even though the canonical energy is unbounded, the other representatives in the series have a bounded from below the 00-component. The theory admits consistent self-interactions with the Yang–Mills gauge symmetry. The Lagrangian couplings preserve the energy–momentum tensor that is unbounded from below, and they do not lead to a stable non-linear theory. The non-Lagrangian couplings are consistent with the existence of a conserved tensor with a 00-component bounded from below. These models are stable at the non-linear level. The dynamics of interacting theory admit a constraint Hamiltonian form. The Hamiltonian density is given by the 00-component of the conserved tensor. In the case of stable interactions, the Poisson bracket and Hamiltonian do not follow from the canonical Ostrogradski construction. Particular attention is paid to the “triply massless” ECS theory, which demonstrates instability even at the free level. It is shown that the introduction of extra scalar field, serving as Higgs, can stabilize the dynamics in the vicinity of the local minimum of energy. The equations of motion of the stable model are non-Lagrangian, but they admit the Hamiltonian form of dynamics with a Hamiltonian that is bounded from below.

Asymmetric polysaccharide-bound graphene electrode configuration with enhanced electrosorption performance for uranium (VI) ions

As an energy-saving and facile technology, the potential of capacitive deionization (CDI) starts to surface in enrichment and recovery of uranium (U(VI)) from aqueous solutions. However, co-ion expulsion effect and poor surface wettability of electrode materials limit the eletrosorption performance. Here, polysaccharides xanthan gum (XG)- and chitosan (CS) -bound porous reduced graphene (RGH) electrodes were rationally designed, and then assembled into asymmetrical electrode configuration for U(VI) eletrosorption. Owing to the introduction of polysaccharide binders, the oppositely charged groups on the surface of cathode and anode weaken the co-ions exclusion effect as well as endow their superior surface hydrophilicity and electroconductivity, which facilitates the electrosorption for U(VI). Meanwhile, the negatively charged carboxylate groups could act as extra micro electric fields to attract U(VI) cations, and form stronge complexation between them. As a consequence, asymmetrical polysaccharide-bound RGH configuration gave rise to a larger removal ratio of 97.9% within 4 h at 1.2 V, as well as 2.5 times faster kinetics than symmetrical PVDF-bound RGH electrode configuration. Moreover, the accumulated adsorption capacity in six adsorption–desorption cycles of the former is up to 1413.0 mg g−1, 75% higher than the latter, which is of practical significance and economic benefit for electrosorption application.

Experimental Results for AlGaN/GaN HEMTs Improving Breakdown Voltage and Output Current by Electric Field Modulation

A depletion-mode AlGaN/GaN high electron mobility transistors (HEMTs) have been proposed in this article with the partial GaN cap, which applies the electric field modulation effect to optimize the surface electric field and two-dimensional electron gas (2DEG) distribution. The 2DEG density under the partial GaN cap is reduced due to the polarization effect formed by the partial GaN cap and AlGaN layers. The surface electric field is reshaped by the electric field modulation effect due to the partial GaN cap, featuring an extra electric field peak far away from the gate edge, which, therefore, improves the breakdown voltage (BV). Moreover, the output current ( ${I}_{\text {DS}}$ ) is also improved slightly resulting from the increased mobility of 2DEG, which compensates for the decrease in the 2DEG density. The experimental BV is increased greatly from 378 V for the conventional AlGaN/GaN HEMTs to 656 V for the depletion-mode partial cap layer AlGaN/GaN HEMTs because of the optimized surface electric field by the electric field modulation effect. The maximum output current ( ${I}_{\text {max}}$ ) is increased from 538 to 558 mA/mm. It is concluded that the BV can be improved significantly and ${I}_{\text {DS}}$ increased slightly for AlGaN/GaN HEMTs by the electric field modulation technique using the partial GaN cap, which optimizes the BV and specific ON-resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON}, \text {sp}}$ ) simultaneously.

Quantum phase space description of a cosmological minimal massive bigravity model

Bimetric gravity theories describes gravitational interactions in the presence of an extra spin-2 field. The Hassan-Rosen (HR) nonlinear massive minimal bigravity theory is a ghost-free bimetric theory formulated with respect a flat, dynamical reference metric. In this work the deformation quantization formalism is applied to a HR cosmological model in the minisuperspace. The quantization procedure is performed explicitly for quantum cosmology in the minisuperspace. The Friedmann-Lema\^itre-Robertson-Walker (FLRW) model with flat metrics is worked out and the computation of the Wigner functions for theHartle-Hawking, Vilenkin and Linde wavefunctions are done numerically and, in the Hartle-Hawking case, also analytically. From the stability analysis in the quantum minisuper phase space it is found an interpretation of the mass of graviton as an emergent cosmological constant and as a measure of the deviation of classical behavior of the Wigner functions. Also, from the Hartle-Hawking case, an interesting relation between the curvature and the mass of graviton in a cusp catastrophe surface is discussed

Polarizable High‐Index Nanoparticles Used for Light‐Induced Crystal‐Silicon Passivation and Dielectric Antenna for High‐Efficiency Solar Cell

Heterojunction crystal‐silicon (c‐Si) solar cells generate current from harvesting light via sweeping excited carriers away under built‐in asymmetry through amorphous silicon layers. However, loss of energy beyond the bandgap is known to hinder their efficiency. Herein, a strategy is provided to convert short‐wavelength energy into a polarization electrical field and the light dielectric antenna effect, where enhanced surface passivation and carrier collection occur simultaneously. By depositing an ultrathin polarizable nanoparticle layer on a transparent conducting oxide (TCO), a light‐induced electrical field is built up by light‐harvesting accumulation, which benefits for c‐Si surface passivation. An enchanting open‐circuit voltage (Voc) of 736.6 mV for the light‐induced field‐effect solar cell is achieved. In addition, the high‐index dielectric nanoparticles generate more photons to be absorbed in the long‐wavelength in c‐Si solar cells, which results in enhanced short‐circuit current (Jsc). As a result, benefiting from the light‐induced building‐up extra field and dielectric antenna effect, the device yields a power conversion efficiency of 22.41%, with the maximal improvement of Voc (≈4 mV), Jsc (≈0.4 mA cm−2), and fill factor (≈1%), respectively. This work provides a strategy to enhance solar cell efficiency by continuously harvesting beyond‐bandgap light to offer an additional asymmetrical field and the light antenna effect.

Development of extra early field pea genotypes using inter-specific hybridization

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Superluminality in DHOST theory with extra scalar

We consider DHOST Ia theory interacting gravitationally with an additional conventional scalar field minimally coupled to gravity. At the linearized level of perturbations about cosmological background, we find that in the presence of a slowly rolling extra scalar field, one of the modes generically propagates at superluminal speed. This result is valid for any stable cosmological background. We identify a subclass of DHOST Ia theories in which this superluminality property is absent, and all modes may propagate (sub)luminally. We discuss possible implications for the interacting DHOST Ia theories.

Higher spins from exotic dualisations

At the free level, a given massless field can be described by an infinite number of different potentials related to each other by dualities. In terms of Young tableaux, dualities replace any number of columns of height hi by columns of height D − 2 − hi, where D is the spacetime dimension: in particular, applying this operation to empty columns gives rise to potentials containing an arbitrary number of groups of D − 2 extra antisymmetric indices. Using the method of parent actions, action principles including these potentials, but also extra fields, can be derived from the usual ones. In this paper, we revisit this off-shell duality and clarify the counting of degrees of freedom and the role of the extra fields. Among others, we consider the examples of the double dual graviton in D = 5 and two cases, one topological and one dynamical, of exotic dualities leading to spin three fields in D = 3.

Studying and applying magnetic dressing with a Bell and Bloom magnetometer

The magnetic dressing phenomenon occurs when spins precessing in a static field (holding field) are subjected to an additional strong alternating field. It is usually studied when such extra field is homogeneous and oscillates in one direction. We study the dynamics of spins under dressing condition in two unusual configurations. In the first instance, an inhomogeneous dressing field produces a space-dependent dressing phenomenon, which helps to operate the magnetometer in a strongly inhomogeneous static field. In the second instance, besides the usual configuration with a static and a strong orthogonal oscillating magnetic fields, we add a secondary oscillating field, which is perpendicular to both. The system shows novel and interesting features that are accurately explained and modelled theoretically. Possible applications of these novel features are briefly discussed.

Numerical investigation of heat flux distribution on the welding groove face in magnetic oscillation arc narrow gap GTAW

Obtaining uniform penetration on welding groove faces is one urgent problem in oscillation arc narrow gap welding; however, the heat flux distribution on the groove face under the deflected welding arc is difficult to investigate by the experimental method. In this article, a unified three-dimensional model is developed to study the heat flux distribution on groove faces. The model includes the electrode, welding arc, workpiece, and their coupling. The plasma arc profile, heat flux characteristics, and weld pool formation were simulated. Based on the simulation results, the following conclusions were contained. The deflecting degree of the welding arc axis is increased with the increasing of extra magnetic-field intensity, and this leads to the change of the distribution of conduction heat flux and electric heat flux. At the groove bottom, both heat fluxes move to one side, and their distribution shape changes from circular to elliptical. At the sidewall, the distribution shape of conduction heat flux is triangular, and that of electrical heat flux is elliptical. The maximum value of heat flux density decreased, and the affected area was increased with the associate of the extra magnetic field. The simulation welding bead was in agreement with the experimental result.

A conductive chlorine ion-imprinted polymer threaded in metal-organic frameworks for electrochemically selective separation of chloride ions

Highly selective ion separation is crucial to engineering applications. In this work, inspired by the working mechanism of biological protein ion channels, inclusion of ion-imprinted conductive polymers inside metal-organic frameworks (MOFs) with size selective effect was considered for the effective separation of ions. In-situ polymerization of polypyrrole (PPy) with anion exchange behavior in the UiO-66 cages was performed to obtain a conductive chlorine ion-imprinted polymer film electrode (Cl-IIP@UiO-66) for the electrochemically selective separation of chloride ions (Cl−) from wastewater. Herein, the chlorine ion-imprinted conductive PPy chains not only tuned the pore size of UiO-66, but also provided ion and electron transport channels at the molecular scale. As a result, the Cl− ion exchange capacity of the Cl-IIP@UiO-66 coated electrode reached to 52.16 mg g−1 with an adsorption equilibrium time less than 4 h under the extra electric field. Meanwhile, the Cl-IIP@UiO-66 film exhibited high separation factors of 9.02, 10.29, 13.41 and 18.50 for Cl−/Br−, Cl−/F−, Cl−/SO42− and Cl−/PO43−, respectively, which was mainly attributed to the anion-imprinting effect and the nanostructure for the selective recognition for Cl− ions. Remarkably, based on the controlled swelling property of MOFs, the Cl-IIP@UiO-66 maintained superior electrochemical reversibility and durability over 98% even after 1000 uptake/release cycles. Hence, it is believed that such a novel electroactive Cl− ion-imprinted film electrode could be a promising candidate for wastewater treatment. Also, it opened a new pathway to develop novel MOF-based electroactive ion exchange materials for various ion separations.

Dark matter, muon anomalous magnetic moment, and the XENON1T excess

A very economic scenario with just three extra scalar fields beyond the Standard Model is invoked to explain the muon anomalous magnetic moment, the requisite relic abundance of dark matter as well as the XENON1T excess through the inelastic down-scattering of the dark scalar.